/*
-----------------------------------------------------------------------------
This source file is part of OGRE
(Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org

Copyright (c) 2000-2011 Torus Knot Software Ltd

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The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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*/
#ifndef __TextureUnitState_H__
#define __TextureUnitState_H__

#include "OgrePrerequisites.h"
#include "OgreCommon.h"
#include "OgreBlendMode.h"
#include "OgreMatrix4.h"
#include "OgreIteratorWrappers.h"
#include "OgreString.h"
#include "OgreTexture.h"

namespace Ogre {
	/** \addtogroup Core
	*  @{
	*/
	/** \addtogroup Materials
	*  @{
	*/
	/** Class representing the state of a single texture unit during a Pass of a
        Technique, of a Material.
    @remarks
        Texture units are pipelines for retrieving texture data for rendering onto
        your objects in the world. Using them is common to both the fixed-function and 
        the programmable (vertex and fragment program) pipeline, but some of the 
        settings will only have an effect in the fixed-function pipeline (for example, 
        setting a texture rotation will have no effect if you use the programmable
        pipeline, because this is overridden by the fragment program). The effect
        of each setting as regards the 2 pipelines is commented in each setting.
    @par
        When I use the term 'fixed-function pipeline' I mean traditional rendering
        where you do not use vertex or fragment programs (shaders). Programmable 
        pipeline means that for this pass you are using vertex or fragment programs.
    */
	class _OgreExport TextureUnitState : public TextureUnitStateAlloc
    {
        friend class RenderSystem;
    public:
        /** Definition of the broad types of texture effect you can apply to a texture unit.
        @note
            Note that these have no effect when using the programmable pipeline, since their
            effect is overridden by the vertex / fragment programs.
        */
        enum TextureEffectType
        {
            /// Generate all texture coords based on angle between camera and vertex
            ET_ENVIRONMENT_MAP,
            /// Generate texture coords based on a frustum
            ET_PROJECTIVE_TEXTURE,
            /// Constant u/v scrolling effect
            ET_UVSCROLL,
			/// Constant u scrolling effect
            ET_USCROLL,
			/// Constant u/v scrolling effect
            ET_VSCROLL,
            /// Constant rotation
            ET_ROTATE,
            /// More complex transform
            ET_TRANSFORM

        };

        /** Enumeration to specify type of envmap.
        @note
            Note that these have no effect when using the programmable pipeline, since their
            effect is overridden by the vertex / fragment programs.
        */
        enum EnvMapType
        {
            /// Envmap based on vector from camera to vertex position, good for planar geometry
            ENV_PLANAR,
            /// Envmap based on dot of vector from camera to vertex and vertex normal, good for curves
            ENV_CURVED,
            /// Envmap intended to supply reflection vectors for cube mapping
            ENV_REFLECTION,
            /// Envmap intended to supply normal vectors for cube mapping
            ENV_NORMAL
        };

        /** Useful enumeration when dealing with procedural transforms.
        @note
            Note that these have no effect when using the programmable pipeline, since their
            effect is overridden by the vertex / fragment programs.
        */
        enum TextureTransformType
        {
            TT_TRANSLATE_U,
            TT_TRANSLATE_V,
            TT_SCALE_U,
            TT_SCALE_V,
            TT_ROTATE
        };

        /** Texture addressing modes - default is TAM_WRAP.
        @note
            These settings are relevant in both the fixed-function and the
            programmable pipeline.
        */
        enum TextureAddressingMode
        {
            /// Texture wraps at values over 1.0
            TAM_WRAP,
            /// Texture mirrors (flips) at joins over 1.0
            TAM_MIRROR,
            /// Texture clamps at 1.0
            TAM_CLAMP,
            /// Texture coordinates outside the range [0.0, 1.0] are set to the border colour
            TAM_BORDER
        };

		/** Texture addressing mode for each texture coordinate. */
		struct UVWAddressingMode
		{
			TextureAddressingMode u, v, w;
		};

        /** Enum identifying the frame indexes for faces of a cube map (not the composite 3D type.
        */
        enum TextureCubeFace
        {
            CUBE_FRONT = 0,
            CUBE_BACK = 1,
            CUBE_LEFT = 2,
            CUBE_RIGHT = 3,
            CUBE_UP = 4,
            CUBE_DOWN = 5
        };

        /** Internal structure defining a texture effect.
        */
        struct TextureEffect {
            TextureEffectType type;
            int subtype;
            Real arg1, arg2;
            WaveformType waveType;
            Real base;
            Real frequency;
            Real phase;
            Real amplitude;
            Controller<Real>* controller;
            const Frustum* frustum;
        };

        /** Texture effects in a multimap paired array
        */
        typedef multimap<TextureEffectType, TextureEffect>::type EffectMap;

        /** Default constructor.
        */
        TextureUnitState(Pass* parent);

        TextureUnitState(Pass* parent, const TextureUnitState& oth );

        TextureUnitState & operator = ( const TextureUnitState& oth );

        /** Default destructor.
        */
        ~TextureUnitState();

        /** Name-based constructor.
        @param
        name The basic name of the texture e.g. brickwall.jpg, stonefloor.png
        @param
        texCoordSet The index of the texture coordinate set to use.
        */
		TextureUnitState( Pass* parent, const String& texName, unsigned int texCoordSet = 0);

        /** Get the name of current texture image for this layer.
        @remarks
        This will either always be a single name for this layer,
        or will be the name of the current frame for an animated
        or otherwise multi-frame texture.
        @note
        Applies to both fixed-function and programmable pipeline.
        */
        const String& getTextureName(void) const;

        /** Sets this texture layer to use a single texture, given the
        name of the texture to use on this layer.
        @note
        Applies to both fixed-function and programmable pipeline.
        */
        void setTextureName( const String& name, TextureType ttype = TEX_TYPE_2D);

		/** Sets this texture layer to use a combination of 6 texture maps, each one relating to a face of a cube.
        @remarks
        Cubic textures are made up of 6 separate texture images. Each one of these is an orthoganal view of the
        world with a FOV of 90 degrees and an aspect ratio of 1:1. You can generate these from 3D Studio by
        rendering a scene to a reflection map of a transparent cube and saving the output files.
        @par
        Cubic maps can be used either for skyboxes (complete wrap-around skies, like space) or as environment
        maps to simulate reflections. The system deals with these 2 scenarios in different ways:
        <ol>
        <li>
        <p>
        for cubic environment maps, the 6 textures are combined into a single 'cubic' texture map which
        is then addressed using 3D texture coordinates. This is required because you don't know what
        face of the box you're going to need to address when you render an object, and typically you
        need to reflect more than one face on the one object, so all 6 textures are needed to be
        'active' at once. Cubic environment maps are enabled by calling this method with the forUVW
        parameter set to true, and then calling setEnvironmentMap(true).
        </p>
        <p>
        Note that not all cards support cubic environment mapping.
        </p>
        </li>
        <li>
        <p>
        for skyboxes, the 6 textures are kept separate and used independently for each face of the skybox.
        This is done because not all cards support 3D cubic maps and skyboxes do not need to use 3D
        texture coordinates so it is simpler to render each face of the box with 2D coordinates, changing
        texture between faces.
        </p>
        <p>
        Skyboxes are created by calling SceneManager::setSkyBox.
        </p>
        </li>
        </ul>
        @note
        Applies to both fixed-function and programmable pipeline.
        @param
        name The basic name of the texture e.g. brickwall.jpg, stonefloor.png. There must be 6 versions
        of this texture with the suffixes _fr, _bk, _up, _dn, _lf, and _rt (before the extension) which
        make up the 6 sides of the box. The textures must all be the same size and be powers of 2 in width & height.
        If you can't make your texture names conform to this, use the alternative method of the same name which takes
        an array of texture names instead.
        @param
        forUVW Set to true if you want a single 3D texture addressable with 3D texture coordinates rather than
        6 separate textures. Useful for cubic environment mapping.
        */
        void setCubicTextureName( const String& name, bool forUVW = false );

        /** Sets this texture layer to use a combination of 6 texture maps, each one relating to a face of a cube.
        @remarks
        Cubic textures are made up of 6 separate texture images. Each one of these is an orthoganal view of the
        world with a FOV of 90 degrees and an aspect ratio of 1:1. You can generate these from 3D Studio by
        rendering a scene to a reflection map of a transparent cube and saving the output files.
        @par
        Cubic maps can be used either for skyboxes (complete wrap-around skies, like space) or as environment
        maps to simulate reflections. The system deals with these 2 scenarios in different ways:
        <ol>
        <li>
        <p>
        for cubic environment maps, the 6 textures are combined into a single 'cubic' texture map which
        is then addressed using 3D texture coordinates. This is required because you don't know what
        face of the box you're going to need to address when you render an object, and typically you
        need to reflect more than one face on the one object, so all 6 textures are needed to be
        'active' at once. Cubic environment maps are enabled by calling this method with the forUVW
        parameter set to true, and then calling setEnvironmentMap(true).
        </p>
        <p>
        Note that not all cards support cubic environment mapping.
        </p>
        </li>
        <li>
        <p>
        for skyboxes, the 6 textures are kept separate and used independently for each face of the skybox.
        This is done because not all cards support 3D cubic maps and skyboxes do not need to use 3D
        texture coordinates so it is simpler to render each face of the box with 2D coordinates, changing
        texture between faces.
        </p>
        <p>
        Skyboxes are created by calling SceneManager::setSkyBox.
        </p>
        </li>
        </ul>
        @note
        Applies to both fixed-function and programmable pipeline.
        @param
        name The basic name of the texture e.g. brickwall.jpg, stonefloor.png. There must be 6 versions
        of this texture with the suffixes _fr, _bk, _up, _dn, _lf, and _rt (before the extension) which
        make up the 6 sides of the box. The textures must all be the same size and be powers of 2 in width & height.
        If you can't make your texture names conform to this, use the alternative method of the same name which takes
        an array of texture names instead.
        @param
        forUVW Set to true if you want a single 3D texture addressable with 3D texture coordinates rather than
        6 separate textures. Useful for cubic environment mapping.
        */
        void setCubicTextureName( const String* const names, bool forUVW = false );

        /** Sets the names of the texture images for an animated texture.
        @remarks
        Animated textures are just a series of images making up the frames of the animation. All the images
        must be the same size, and their names must have a frame number appended before the extension, e.g.
        if you specify a name of "wall.jpg" with 3 frames, the image names must be "wall_0.jpg", "wall_1.jpg"
        and "wall_2.jpg".
        @par
        You can change the active frame on a texture layer by calling the setCurrentFrame method.
        @note
        If you can't make your texture images conform to the naming standard layed out here, you
        can call the alternative setAnimatedTextureName method which takes an array of names instead.
        @note
        Applies to both fixed-function and programmable pipeline.
        @param
        name The base name of the textures to use e.g. wall.jpg for frames wall_0.jpg, wall_1.jpg etc.
        @param
        numFrames The number of frames in the sequence.
        @param
        duration The length of time it takes to display the whole animation sequence, in seconds.
        If 0, no automatic transition occurs.
        */
        void setAnimatedTextureName( const String& name, unsigned int numFrames, Real duration = 0 );

        /** Sets the names of the texture images for an animated texture.
        @remarks
        This an alternative method to the one where you specify a single name and let the system derive
        the names of each frame, incase your images can't conform to this naming standard.
        @par
        Animated textures are just a series of images making up the frames of the animation. All the images
        must be the same size, and you must provide their names as an array in the first parameter.
        You can change the active frame on a texture layer by calling the setCurrentFrame method.
        @note
        If you can make your texture images conform to a naming standard of basicName_frame.ext, you
        can call the alternative setAnimatedTextureName method which just takes a base name instead.
        @note
        Applies to both fixed-function and programmable pipeline.
        @param
        names Pointer to array of names of the textures to use, in frame order.
        @param
        numFrames The number of frames in the sequence.
        @param
        duration The length of time it takes to display the whole animation sequence, in seconds.
        If 0, no automatic transition occurs.
        */
        void setAnimatedTextureName( const String* const names, unsigned int numFrames, Real duration = 0 );

        /** Returns the width and height of the texture in the given frame.
        */
        std::pair< size_t, size_t > getTextureDimensions( unsigned int frame = 0 ) const;

        /** Changes the active frame in an animated or multi-image texture.
        @remarks
        An animated texture (or a cubic texture where the images are not combined for 3D use) is made up of
        a number of frames. This method sets the active frame.
        @note
        Applies to both fixed-function and programmable pipeline.
        */
        void setCurrentFrame( unsigned int frameNumber );

        /** Gets the active frame in an animated or multi-image texture layer.
        @note
        Applies to both fixed-function and programmable pipeline.
        */
        unsigned int getCurrentFrame(void) const;

        /** Gets the name of the texture associated with a frame number.
            Throws an exception if frameNumber exceeds the number of stored frames.
        @note
        Applies to both fixed-function and programmable pipeline.
        */
        const String& getFrameTextureName(unsigned int frameNumber) const;

        /** Sets the name of the texture associated with a frame.
        @param name The name of the texture
        @param frameNumber The frame the texture name is to be placed in
        @note
        Throws an exception if frameNumber exceeds the number of stored frames.
        Applies to both fixed-function and programmable pipeline.
        */
        void setFrameTextureName(const String& name, unsigned int frameNumber);

        /** Add a Texture name to the end of the frame container.
        @param name The name of the texture
        @note
        Applies to both fixed-function and programmable pipeline.
        */
        void addFrameTextureName(const String& name);
        /** deletes a specific texture frame.  The texture used is not deleted but the
            texture will no longer be used by the Texture Unit.  An exception is raised
            if the frame number exceeds the number of actual frames.
        @param frameNumber The frame number of the texture to be deleted.
        @note
        Applies to both fixed-function and programmable pipeline.
        */
        void deleteFrameTextureName(const size_t frameNumber);
        /** Gets the number of frames for a texture.
        @note
        Applies to both fixed-function and programmable pipeline.
        */
        unsigned int getNumFrames(void) const;


		/** The type of unit to bind the texture settings to. */
		enum BindingType
		{
			/** Regular fragment processing unit - the default. */
			BT_FRAGMENT = 0,
			/** Vertex processing unit - indicates this unit will be used for 
				a vertex texture fetch.
			*/
			BT_VERTEX = 1
		};
		/** Enum identifying the type of content this texture unit contains.
		*/
		enum ContentType
		{
			/// Normal texture identified by name
			CONTENT_NAMED = 0,
			/// A shadow texture, automatically bound by engine
			CONTENT_SHADOW = 1,
			/// A compositor texture, automatically linked to active viewport's chain
			CONTENT_COMPOSITOR = 2
		};

		/** Sets the type of unit these texture settings should be bound to. 
		@remarks
			Some render systems, when implementing vertex texture fetch, separate
			the binding of textures for use in the vertex program versus those
			used in fragment programs. This setting allows you to target the
			vertex processing unit with a texture binding, in those cases. For
			rendersystems which have a unified binding for the vertex and fragment
			units, this setting makes no difference.
		*/
		void setBindingType(BindingType bt);

		/** Gets the type of unit these texture settings should be bound to.  
		*/
		BindingType getBindingType(void) const;

		/** Set the type of content this TextureUnitState references.
		@remarks
			The default is to reference a standard named texture, but this unit
			can also reference automated content like a shadow texture.
		*/
		void setContentType(ContentType ct);
		/** Get the type of content this TextureUnitState references. */
		ContentType getContentType(void) const;

        /** Returns true if this texture unit is either a series of 6 2D textures, each
            in it's own frame, or is a full 3D cube map. You can tell which by checking
            getTextureType.
        @note
        Applies to both fixed-function and programmable pipeline.
        */
        bool isCubic(void) const;

        /** Returns true if this texture layer uses a composite 3D cubic texture.
        @note
        Applies to both fixed-function and programmable pipeline.
        */
        bool is3D(void) const;

        /** Returns the type of this texture.
        @note
        Applies to both fixed-function and programmable pipeline.
        */
        TextureType getTextureType(void) const;

        /** Sets the desired pixel format when load the texture.
        */
        void setDesiredFormat(PixelFormat desiredFormat);

        /** Gets the desired pixel format when load the texture.
        */
        PixelFormat getDesiredFormat(void) const;

        /** Sets how many mipmaps have been requested for the texture.
		*/
        void setNumMipmaps(int numMipmaps);

        /** Gets how many mipmaps have been requested for the texture.
		*/
        int getNumMipmaps(void) const;

		/** Sets whether this texture is requested to be loaded as alpha if single channel
		*/
        void setIsAlpha(bool isAlpha);

		/** Gets whether this texture is requested to be loaded as alpha if single channel
		*/
        bool getIsAlpha(void) const;

		/// @copydoc Texture::setHardwareGammaEnabled
		void setHardwareGammaEnabled(bool enabled);
		/// @copydoc Texture::isHardwareGammaEnabled
		bool isHardwareGammaEnabled() const;

        /** Gets the index of the set of texture co-ords this layer uses.
        @note
        Applies to both fixed-function and programmable pipeline.
        */
        unsigned int getTextureCoordSet(void) const;

        /** Sets the index of the set of texture co-ords this layer uses.
        @note
        Default is 0 for all layers. Only change this if you have provided multiple texture co-ords per
        vertex.
        @note
        Applies to both fixed-function and programmable pipeline.
        */
        void setTextureCoordSet(unsigned int set);

        /** Sets a matrix used to transform any texture coordinates on this layer.
        @remarks
        Texture coordinates can be modified on a texture layer to create effects like scrolling
        textures. A texture transform can either be applied to a layer which takes the source coordinates
        from a fixed set in the geometry, or to one which generates them dynamically (e.g. environment mapping).
        @par
        It's obviously a bit impractical to create scrolling effects by calling this method manually since you
        would have to call it every framw with a slight alteration each time, which is tedious. Instead
        you can use the ControllerManager class to create a Controller object which will manage the
        effect over time for you. See the ControllerManager::createTextureScroller and it's sibling methods for details.<BR>
        In addition, if you want to set the individual texture transformations rather than concatenating them
        yourself, use setTextureScroll, setTextureScale and setTextureRotate.
        @note
        Has no effect in the programmable pipeline.
        */
        void setTextureTransform(const Matrix4& xform);

        /** Gets the current texture transformation matrix.
        @remarks
        Causes a reclaculation of the matrix if any parameters have been changed via
        setTextureScroll, setTextureScale and setTextureRotate.
        @note
        Has no effect in the programmable pipeline.
        */
        const Matrix4& getTextureTransform(void) const;

        /** Sets the translation offset of the texture, ie scrolls the texture.
        @remarks
        This method sets the translation element of the texture transformation, and is easier to use than setTextureTransform if
        you are combining translation, scaling and rotation in your texture transformation. Again if you want
        to animate these values you need to use a Controller
        @note
        Has no effect in the programmable pipeline.
        @param u The amount the texture should be moved horizontally (u direction).
        @param v The amount the texture should be moved vertically (v direction).
        @see
        ControllerManager, Controller
        */
        void setTextureScroll(Real u, Real v);

        /** As setTextureScroll, but sets only U value.
        @note
        Has no effect in the programmable pipeline.
        */
        void setTextureUScroll(Real value);
        // get texture uscroll value
        Real getTextureUScroll(void) const;

        /** As setTextureScroll, but sets only V value.
        @note
        Has no effect in the programmable pipeline.
        */
        void setTextureVScroll(Real value);
        // get texture vscroll value
        Real getTextureVScroll(void) const;

        /** As setTextureScale, but sets only U value.
        @note
        Has no effect in the programmable pipeline.
        */
        void setTextureUScale(Real value);
        // get texture uscale value
        Real getTextureUScale(void) const;

        /** As setTextureScale, but sets only V value.
        @note
        Has no effect in the programmable pipeline.
        */
        void setTextureVScale(Real value);
        // get texture vscale value
        Real getTextureVScale(void) const;

        /** Sets the scaling factor applied to texture coordinates.
        @remarks
        This method sets the scale element of the texture transformation, and is easier to use than
        setTextureTransform if you are combining translation, scaling and rotation in your texture transformation. Again if you want
        to animate these values you need to use a Controller (see ControllerManager and it's methods for
        more information).
        @note
        Has no effect in the programmable pipeline.
        @param
        uScale The value by which the texture is to be scaled horizontally.
        @param
        vScale The value by which the texture is to be scaled vertically.
        */
        void setTextureScale(Real uScale, Real vScale);

        /** Sets the anticlockwise rotation factor applied to texture coordinates.
        @remarks
        This sets a fixed rotation angle - if you wish to animate this, see the
        ControllerManager::createTextureRotater method.
        @note
        Has no effect in the programmable pipeline.
        @param
        angle The angle of rotation (anticlockwise).
        */
        void setTextureRotate(const Radian& angle);
        // get texture rotation effects angle value
        const Radian& getTextureRotate(void) const;

        /** Gets the texture addressing mode for a given coordinate, 
		 	i.e. what happens at uv values above 1.0.
        @note
        	The default is TAM_WRAP i.e. the texture repeats over values of 1.0.
        */
        const UVWAddressingMode& getTextureAddressingMode(void) const;

        /** Sets the texture addressing mode, i.e. what happens at uv values above 1.0.
        @note
        The default is TAM_WRAP i.e. the texture repeats over values of 1.0.
		@note This is a shortcut method which sets the addressing mode for all
			coordinates at once; you can also call the more specific method
			to set the addressing mode per coordinate.
        @note
        This applies for both the fixed-function and programmable pipelines.
        */
        void setTextureAddressingMode( TextureAddressingMode tam);

        /** Sets the texture addressing mode, i.e. what happens at uv values above 1.0.
        @note
        The default is TAM_WRAP i.e. the texture repeats over values of 1.0.
        @note
        This applies for both the fixed-function and programmable pipelines.
		*/
        void setTextureAddressingMode( TextureAddressingMode u, 
			TextureAddressingMode v, TextureAddressingMode w);

        /** Sets the texture addressing mode, i.e. what happens at uv values above 1.0.
        @note
        The default is TAM_WRAP i.e. the texture repeats over values of 1.0.
        @note
        This applies for both the fixed-function and programmable pipelines.
		*/
        void setTextureAddressingMode( const UVWAddressingMode& uvw);

        /** Sets the texture border colour.
        @note
            The default is ColourValue::Black, and this value only used when addressing mode
            is TAM_BORDER.
        @note
            This applies for both the fixed-function and programmable pipelines.
		*/
        void setTextureBorderColour(const ColourValue& colour);

        /** Sets the texture border colour.
        @note
            The default is ColourValue::Black, and this value only used when addressing mode
            is TAM_BORDER.
		*/
        const ColourValue& getTextureBorderColour(void) const;

		/** Setting advanced blending options.
        @remarks
        This is an extended version of the TextureUnitState::setColourOperation method which allows
        extremely detailed control over the blending applied between this and earlier layers.
        See the IMPORTANT note below about the issues between mulitpass and multitexturing that
        using this method can create.
        @par
        Texture colour operations determine how the final colour of the surface appears when
        rendered. Texture units are used to combine colour values from various sources (ie. the
        diffuse colour of the surface from lighting calculations, combined with the colour of
        the texture). This method allows you to specify the 'operation' to be used, ie. the
        calculation such as adds or multiplies, and which values to use as arguments, such as
        a fixed value or a value from a previous calculation.
        @par
        The defaults for each layer are:
        <ul>
        <li>op = LBX_MODULATE</li>
        <li>source1 = LBS_TEXTURE</li>
        <li>source2 = LBS_CURRENT</li>
        </ul>
        ie. each layer takes the colour results of the previous layer, and multiplies them
        with the new texture being applied. Bear in mind that colours are RGB values from
        0.0 - 1.0 so multiplying them together will result in values in the same range,
        'tinted' by the multiply. Note however that a straight multiply normally has the
        effect of darkening the textures - for this reason there are brightening operations
        like LBO_MODULATE_X2. See the LayerBlendOperation and LayerBlendSource enumerated
        types for full details.
        @note
        Because of the limitations on some underlying APIs (Direct3D included)
        the LBS_TEXTURE argument can only be used as the first argument, not the second.
        @par
        The final 3 parameters are only required if you decide to pass values manually
        into the operation, i.e. you want one or more of the inputs to the colour calculation
        to come from a fixed value that you supply. Hence you only need to fill these in if
        you supply LBS_MANUAL to the corresponding source, or use the LBX_BLEND_MANUAL
        operation.
        @warning
        Ogre tries to use multitexturing hardware to blend texture layers
        together. However, if it runs out of texturing units (e.g. 2 of a GeForce2, 4 on a
        GeForce3) it has to fall back on multipass rendering, i.e. rendering the same object
        multiple times with different textures. This is both less efficient and there is a smaller
        range of blending operations which can be performed. For this reason, if you use this method
        you MUST also call TextureUnitState::setColourOpMultipassFallback to specify which effect you
        want to fall back on if sufficient hardware is not available.
        @note
        This has no effect in the programmable pipeline.
        @param
        If you wish to avoid having to do this, use the simpler TextureUnitState::setColourOperation method
        which allows less flexible blending options but sets up the multipass fallback automatically,
        since it only allows operations which have direct multipass equivalents.
        @param
        op The operation to be used, e.g. modulate (multiply), add, subtract
        @param
        source1 The source of the first colour to the operation e.g. texture colour
        @param
        source2 The source of the second colour to the operation e.g. current surface colour
        @param
        arg1 Manually supplied colour value (only required if source1 = LBS_MANUAL)
        @param
        arg2 Manually supplied colour value (only required if source2 = LBS_MANUAL)
        @param
        manualBlend Manually supplied 'blend' value - only required for operations
        which require manual blend e.g. LBX_BLEND_MANUAL
        */
        void setColourOperationEx(
            LayerBlendOperationEx op,
            LayerBlendSource source1 = LBS_TEXTURE,
            LayerBlendSource source2 = LBS_CURRENT,

            const ColourValue& arg1 = ColourValue::White,
            const ColourValue& arg2 = ColourValue::White,

            Real manualBlend = 0.0);

        /** Determines how this texture layer is combined with the one below it (or the diffuse colour of
        the geometry if this is layer 0).
        @remarks
        This method is the simplest way to blend tetxure layers, because it requires only one parameter,
        gives you the most common blending types, and automatically sets up 2 blending methods: one for
        if single-pass multitexturing hardware is available, and another for if it is not and the blending must
        be achieved through multiple rendering passes. It is, however, quite limited and does not expose
        the more flexible multitexturing operations, simply because these can't be automatically supported in
        multipass fallback mode. If want to use the fancier options, use TextureUnitState::setColourOperationEx,
        but you'll either have to be sure that enough multitexturing units will be available, or you should
        explicitly set a fallback using TextureUnitState::setColourOpMultipassFallback.
        @note
        The default method is LBO_MODULATE for all layers.
        @note
        This option has no effect in the programmable pipeline.
        @param
        op One of the LayerBlendOperation enumerated blending types.
        */
        void setColourOperation( const LayerBlendOperation op);

        /** Sets the multipass fallback operation for this layer, if you used TextureUnitState::setColourOperationEx
        and not enough multitexturing hardware is available.
        @remarks
        Because some effects exposed using TextureUnitState::setColourOperationEx are only supported under
        multitexturing hardware, if the hardware is lacking the system must fallback on multipass rendering,
        which unfortunately doesn't support as many effects. This method is for you to specify the fallback
        operation which most suits you.
        @par
        You'll notice that the interface is the same as the Material::setSceneBlending method; this is
        because multipass rendering IS effectively scene blending, since each layer is rendered on top
        of the last using the same mechanism as making an object transparent, it's just being rendered
        in the same place repeatedly to get the multitexture effect.
        @par
        If you use the simpler (and hence less flexible) TextureUnitState::setColourOperation method you
        don't need to call this as the system sets up the fallback for you.
        @note
        This option has no effect in the programmable pipeline, because there is no multipass fallback
        and multitexture blending is handled by the fragment shader.
        */
        void setColourOpMultipassFallback( const SceneBlendFactor sourceFactor, const SceneBlendFactor destFactor);

        /** Get multitexturing colour blending mode.
        */
        const LayerBlendModeEx& getColourBlendMode(void) const;

        /** Get multitexturing alpha blending mode.
        */
        const LayerBlendModeEx& getAlphaBlendMode(void) const;

        /** Get the multipass fallback for colour blending operation source factor.
        */
        SceneBlendFactor getColourBlendFallbackSrc(void) const;

        /** Get the multipass fallback for colour blending operation destination factor.
        */
        SceneBlendFactor getColourBlendFallbackDest(void) const;

        /** Sets the alpha operation to be applied to this texture.
        @remarks
        This works in exactly the same way as setColourOperation, except
        that the effect is applied to the level of alpha (i.e. transparency)
        of the texture rather than its colour. When the alpha of a texel (a pixel
        on a texture) is 1.0, it is opaque, wheras it is fully transparent if the
        alpha is 0.0. Please refer to the setColourOperation method for more info.
        @param
        op The operation to be used, e.g. modulate (multiply), add, subtract
        @param
        source1 The source of the first alpha value to the operation e.g. texture alpha
        @param
        source2 The source of the second alpha value to the operation e.g. current surface alpha
        @param
        arg1 Manually supplied alpha value (only required if source1 = LBS_MANUAL)
        @param
        arg2 Manually supplied alpha value (only required if source2 = LBS_MANUAL)
        @param
        manualBlend Manually supplied 'blend' value - only required for operations
        which require manual blend e.g. LBX_BLEND_MANUAL
        @see
        setColourOperation
        @note
        This option has no effect in the programmable pipeline.
        */
        void setAlphaOperation(LayerBlendOperationEx op,
            LayerBlendSource source1 = LBS_TEXTURE,
            LayerBlendSource source2 = LBS_CURRENT,
            Real arg1 = 1.0,
            Real arg2 = 1.0,
            Real manualBlend = 0.0);

        /** Generic method for setting up texture effects.
        @remarks
        Allows you to specify effects directly by using the TextureEffectType enumeration. The
        arguments that go with it depend on the effect type. Only one effect of
        each type can be applied to a texture layer.
        @par
        This method is used internally by Ogre but it is better generally for applications to use the
        more intuitive specialised methods such as setEnvironmentMap and setScroll.
        @note
        This option has no effect in the programmable pipeline.
        */
        void addEffect(TextureEffect& effect);

        /** Turns on/off texture coordinate effect that makes this layer an environment map.
        @remarks
        Environment maps make an object look reflective by using the object's vertex normals relative
        to the camera view to generate texture coordinates.
        @par
        The vectors generated can either be used to address a single 2D texture which
        is a 'fish-eye' lens view of a scene, or a 3D cubic environment map which requires 6 textures
        for each side of the inside of a cube. The type depends on what texture you set up - if you use the
        setTextureName method then a 2D fisheye lens texture is required, whereas if you used setCubicTextureName
        then a cubic environemnt map will be used.
        @par
        This effect works best if the object has lots of gradually changing normals. The texture also
        has to be designed for this effect - see the example spheremap.png included with the sample
        application for a 2D environment map; a cubic map can be generated by rendering 6 views of a
        scene to each of the cube faces with orthoganal views.
        @note
        Enabling this disables any other texture coordinate generation effects.
        However it can be combined with texture coordinate modification functions, which then operate on the
        generated coordinates rather than static model texture coordinates.
        @param
        enable True to enable, false to disable
        @param
        planar If set to true, instead of being based on normals the environment effect is based on
        vertex positions. This is good for planar surfaces.
        @note
        This option has no effect in the programmable pipeline.
        */
        void setEnvironmentMap(bool enable, EnvMapType envMapType = ENV_CURVED);

        /** Sets up an animated scroll for the texture layer.
        @note
        Useful for creating constant scrolling effects on a texture layer (for varying scrolls, see setTransformAnimation).
        @param
        uSpeed The number of horizontal loops per second (+ve=moving right, -ve = moving left)
        @param
        vSpeed The number of vertical loops per second (+ve=moving up, -ve= moving down)
        @note
        This option has no effect in the programmable pipeline.
        */
        void setScrollAnimation(Real uSpeed, Real vSpeed);

        /** Sets up an animated texture rotation for this layer.
        @note
        Useful for constant rotations (for varying rotations, see setTransformAnimation).
        @param
        speed The number of complete anticlockwise revolutions per second (use -ve for clockwise)
        @note
        This option has no effect in the programmable pipeline.
        */
        void setRotateAnimation(Real speed);

        /** Sets up a general time-relative texture modification effect.
        @note
        This can be called multiple times for different values of ttype, but only the latest effect
        applies if called multiple time for the same ttype.
        @param
        ttype The type of transform, either translate (scroll), scale (stretch) or rotate (spin)
        @param
        waveType The shape of the wave, see WaveformType enum for details
        @param
        base The base value for the function (range of output = {base, base + amplitude})
        @param
        frequency The speed of the wave in cycles per second
        @param
        phase The offset of the start of the wave, e.g. 0.5 to start half-way through the wave
        @param
        amplitude Scales the output so that instead of lying within 0..1 it lies within 0..1*amplitude for exaggerated effects
        @note
        This option has no effect in the programmable pipeline.
        */
        void setTransformAnimation( const TextureTransformType ttype,
            const WaveformType waveType, Real base = 0, Real frequency = 1, Real phase = 0, Real amplitude = 1 );


        /** Enables or disables projective texturing on this texture unit.
        @remarks
            Projective texturing allows you to generate texture coordinates 
            based on a Frustum, which gives the impression that a texture is
            being projected onto the surface. Note that once you have called
            this method, the texture unit continues to monitor the Frustum you 
            passed in and the projection will change if you can alter it. It also
            means that you must ensure that the Frustum object you pass a pointer
            to remains in existence for as long as this TextureUnitState does.
        @par
            This effect cannot be combined with other texture generation effects, 
            such as environment mapping. It also has no effect on passes which 
            have a vertex program enabled - projective texturing has to be done
            in the vertex program instead.
        @param enabled Whether to enable / disable
        @param projectionSettings The Frustum which will be used to derive the 
            projection parameters.
        */
        void setProjectiveTexturing(bool enabled, const Frustum* projectionSettings = 0);

        /** Removes all effects applied to this texture layer.
        */
        void removeAllEffects(void);

        /** Removes a single effect applied to this texture layer.
        @note
        Because you can only have 1 effect of each type (e.g. 1 texture coordinate generation) applied
        to a layer, only the effect type is required.
        */
        void removeEffect( const TextureEffectType type );

        /** Determines if this texture layer is currently blank.
        @note
        This can happen if a texture fails to load or some other non-fatal error. Worth checking after
        setting texture name.
        */
        bool isBlank(void) const;

        /** Sets this texture layer to be blank.
        */
        void setBlank(void);

		/** Tests if the texture associated with this unit has failed to load.
		*/
		bool isTextureLoadFailing() const { return mTextureLoadFailed; }

		/** Tells the unit to retry loading the texture if it had failed to load.
		*/
		void retryTextureLoad() { mTextureLoadFailed = false; }

        // get texture effects in a multimap paired array
        const EffectMap& getEffects(void) const;
        // get the animated-texture animation duration
        Real getAnimationDuration(void) const;

        /** Set the texture filtering for this unit, using the simplified interface.
        @remarks
            You also have the option of specifying the minification, magnification
            and mip filter individually if you want more control over filtering
            options. See the alternative setTextureFiltering methods for details.
        @note
        This option applies in both the fixed function and the programmable pipeline.
        @param filterType The high-level filter type to use.
        */
        void setTextureFiltering(TextureFilterOptions filterType);
        /** Set a single filtering option on this texture unit. 
        @params ftype The filtering type to set
        @params opts The filtering option to set
        */
        void setTextureFiltering(FilterType ftype, FilterOptions opts);
        /** Set a the detailed filtering options on this texture unit. 
        @params minFilter The filtering to use when reducing the size of the texture. 
            Can be FO_POINT, FO_LINEAR or FO_ANISOTROPIC
        @params magFilter The filtering to use when increasing the size of the texture
            Can be FO_POINT, FO_LINEAR or FO_ANISOTROPIC
        @params mipFilter The filtering to use between mip levels
            Can be FO_NONE (turns off mipmapping), FO_POINT or FO_LINEAR (trilinear filtering)
        */
        void setTextureFiltering(FilterOptions minFilter, FilterOptions magFilter, FilterOptions mipFilter);
        // get the texture filtering for the given type
        FilterOptions getTextureFiltering(FilterType ftpye) const;

        /** Sets the anisotropy level to be used for this texture level.
        @par maxAniso The maximal anisotropy level, should be between 2 and the maximum supported by hardware (1 is the default, ie. no anisotrophy).
        @note
        This option applies in both the fixed function and the programmable pipeline.
        */
        void setTextureAnisotropy(unsigned int maxAniso);
        // get this layer texture anisotropy level
        unsigned int getTextureAnisotropy() const;

		/** Sets the bias value applied to the mipmap calculation.
		@remarks
			You can alter the mipmap calculation by biasing the result with a 
			single floating point value. After the mip level has been calculated,
			this bias value is added to the result to give the final mip level.
			Lower mip levels are larger (higher detail), so a negative bias will
			force the larger mip levels to be used, and a positive bias
			will cause smaller mip levels to be used. The bias values are in 
			mip levels, so a -1 bias will force mip levels one larger than by the
			default calculation.
		@param bias The bias value as described above, can be positive or negative.
		*/
		void setTextureMipmapBias(float bias) { mMipmapBias = bias; }
		/** Gets the bias value applied to the mipmap calculation.
		@see TextureUnitState::setTextureMipmapBias
		*/
		float getTextureMipmapBias(void) const { return mMipmapBias; }

		/** Set the compositor reference for this texture unit state.
		@remarks 
			Only valid when content type is compositor.
		@param compositorName the name of the compositor to reference
		@param textureName the name of the texture to reference
		@param mrtIndex the index of the wanted texture, if referencing an MRT
		*/
		void setCompositorReference(const String& compositorName, const String& textureName, size_t mrtIndex = 0);

		/** Gets the name of the compositor that this texture referneces */
		const String& getReferencedCompositorName() const { return mCompositorRefName; }
		/** Gets the name of the texture in the compositor that this texture references */
		const String& getReferencedTextureName() const { return mCompositorRefTexName; }
		/** Gets the MRT index of the texture in the compositor that this texture references */ 
		size_t getReferencedMRTIndex() const { return mCompositorRefMrtIndex; }
	
        /// Gets the parent Pass object
        Pass* getParent(void) const { return mParent; }

		/** Internal method for preparing this object for load, as part of Material::prepare*/
		void _prepare(void);
		/** Internal method for undoing the preparation this object as part of Material::unprepare*/
		void _unprepare(void);
		/** Internal method for loading this object as part of Material::load */
		void _load(void);
		/** Internal method for unloading this object as part of Material::unload */
		void _unload(void);
        /// Returns whether this unit has texture coordinate generation that depends on the camera
        bool hasViewRelativeTextureCoordinateGeneration(void) const;

        // Is this loaded?
        bool isLoaded(void) const;
        /** Tells the class that it needs recompilation. */
        void _notifyNeedsRecompile(void);

        /** Set the name of the Texture Unit State
        @remarks
            The name of the Texture Unit State is optional.  Its usefull in material scripts where a material could inherit
            from another material and only want to modify a particalar Texture Unit State.
        */
        void setName(const String& name);
        /// get the name of the Texture Unit State
        const String& getName(void) const { return mName; }

        /** Set the alias name used for texture frame names
        @param name can be any sequence of characters and does not have to be unique           
        */
        void setTextureNameAlias(const String& name);
        /** gets the Texture Name Alias of the Texture Unit.
        */
        const String& getTextureNameAlias(void) const { return mTextureNameAlias;}

        /** Applies texture names to Texture Unit State with matching texture name aliases.
            If no matching aliases are found then the TUS state does not change.
        @remarks
            Cubic, 1d, 2d, and 3d textures are determined from current state of the Texture Unit.
            Assumes animated frames are sequentially numbered in the name.
            If matching texture aliases are found then true is returned.

        @param
            aliasList is a map container of texture alias, texture name pairs
        @param
            apply set true to apply the texture aliases else just test to see if texture alias matches are found.
        @return
            True if matching texture aliases were found in the Texture Unit State.
        */
        bool applyTextureAliases(const AliasTextureNamePairList& aliasList, const bool apply = true);

		/** Notify this object that its parent has changed */
		void _notifyParent(Pass* parent);

		/** Get the texture pointer for the current frame. */
		const TexturePtr& _getTexturePtr(void) const;
		/** Get the texture pointer for a given frame. */
		const TexturePtr& _getTexturePtr(size_t frame) const;
	
		/** Set the texture pointer for the current frame (internal use only!). */
		void _setTexturePtr(const TexturePtr& texptr);
		/** Set the texture pointer for a given frame (internal use only!). */
		void _setTexturePtr(const TexturePtr& texptr, size_t frame);

		/** Gets the animation controller (as created because of setAnimatedTexture)
			if it exists.
		*/
		Controller<Real>* _getAnimController() const { return mAnimController; }
protected:
        // State
        /// The current animation frame.
        unsigned int mCurrentFrame;

        /// Duration of animation in seconds
        Real mAnimDuration;            
        bool mCubic; // is this a series of 6 2D textures to make up a cube?
		
        TextureType mTextureType; 
        PixelFormat mDesiredFormat;
		int mTextureSrcMipmaps; // Request number of mipmaps

        unsigned int mTextureCoordSetIndex;
        UVWAddressingMode mAddressMode;
        ColourValue mBorderColour;

        LayerBlendModeEx mColourBlendMode;
        SceneBlendFactor mColourBlendFallbackSrc;
        SceneBlendFactor mColourBlendFallbackDest;

        LayerBlendModeEx mAlphaBlendMode;
        mutable bool mTextureLoadFailed;
        bool mIsAlpha;
		bool mHwGamma;

        mutable bool mRecalcTexMatrix;
        Real mUMod, mVMod;
        Real mUScale, mVScale;
        Radian mRotate;
        mutable Matrix4 mTexModMatrix;

        /// Texture filtering - minification
        FilterOptions mMinFilter;
        /// Texture filtering - magnification
        FilterOptions mMagFilter;
        /// Texture filtering - mipmapping
        FilterOptions mMipFilter;
        ///Texture anisotropy
        unsigned int mMaxAniso;
		/// Mipmap bias (always float, not Real)
		float mMipmapBias;

        bool mIsDefaultAniso;
        bool mIsDefaultFiltering;
		/// Binding type (fragment or vertex pipeline)
		BindingType mBindingType;
		/// Content type of texture (normal loaded texture, auto-texture)
		ContentType mContentType;
		/// The index of the referenced texture if referencing an MRT in a compositor
		size_t mCompositorRefMrtIndex;

        //-----------------------------------------------------------------------------
        // Complex members (those that can't be copied using memcpy) are at the end to 
        // allow for fast copying of the basic members.
        //
        vector<String>::type mFrames;
		mutable vector<TexturePtr>::type mFramePtrs;
        String mName;               // optional name for the TUS
        String mTextureNameAlias;       // optional alias for texture frames
        EffectMap mEffects;
		///The data that references the compositor
		String mCompositorRefName;
		String mCompositorRefTexName;
        //-----------------------------------------------------------------------------

        //-----------------------------------------------------------------------------
        // Pointer members (those that can't be copied using memcpy), and MUST
        // preserving even if assign from others
        //
        Pass* mParent;
        Controller<Real>* mAnimController;
        //-----------------------------------------------------------------------------


        /** Internal method for calculating texture matrix.
        */
        void recalcTextureMatrix(void) const;

        /** Internal method for creating animation controller.
        */
        void createAnimController(void);

        /** Internal method for creating texture effect controller.
        */
        void createEffectController(TextureEffect& effect);

		/** Internal method for ensuring the texture for a given frame is prepared. */
		void ensurePrepared(size_t frame) const;
		/** Internal method for ensuring the texture for a given frame is loaded. */
		void ensureLoaded(size_t frame) const;


    };

	/** @} */
	/** @} */

}

#endif
